The present invention relates generally to air return bulkheads for trailers for insuring proper flow of refrigerated air therein, and more specifically to universal-mount air return bulkheads which may be rapidly modified to fit on different trailer walls with differently-sized makes and models of refrigeration units thereon.
Refrigerated trailers are commonly used to transport perishable cargo on roadways in order to distribute the cargo to consumers in a fresh condition. These refrigerated trailers are specially designed for effective cooling of the cargo. The refrigeration unit for the trailer is generally mounted on the front wall of the trailer with a portion protruding into the interior of the trailer. The refrigerator inlet is located on the lower portion of the refrigerator adjacent the trailer interior front wall, and the refrigerator outlet is located on the top portion of the refrigerator near the trailer ceiling. As a result, warmer air is pulled from the trailer front wall, cooled, and blown along the ceiling of the trailer toward the trailer rear wall. The cargo is stacked on the trailer floor so that it is spaced from the trailer ceiling and the walls of the trailer. The floor of the trailer may be a false floor with a space located beneath, or as illustrated by the drawings in U.S. Pat. No. 2,923,384 to Black, the trailer floor may comprise a series of rails, ridges, or similar raised structures with lengths oriented from the front of the trailer to the rear of the trailer. In either case, the floor supports the cargo but allows refrigerated air to flow rearward along the trailer ceiling, along the trailer rear wall, and beneath the cargo and toward the front of the trailer. The refrigerator inlet then pulls the air in so that it may be recooled and again ejected rearwardly along the trailer ceiling. This cooling methodology allows a steady recirculating flow of refrigerated air to surround the entirety of the cargo, thereby keeping it at a cold temperature.
However, it has been found that cargo can sometimes shift during transport and slide against the front or rear wall of the trailer to block the circulating air. To prevent this problem, a bulkhead including a series of ribs or ridges thereon is frequently mounted to the front wall below the refrigerator inlet This bulkhead, which is often called a xe2x80x9clattice-typexe2x80x9d air return bulkhead, preserves the passage of air to the refrigerator inlet along the front wall even if cargo shifts against it. The spacing between the ridges is such that cargo cannot fit therein, thereby preventing shifting cargo from moving between or behind the ridges and obstructing the circulation of air. The lattice-type air return bulkhead may even extend over the refrigerator and toward the trailer ceiling to protect the refrigerator from damage from shifting cargo. One lattice-style air return bulkhead sold by Donovan Enterprises (LaGrange, Ga.) includes a series of vertically-oriented beams mounted to the trailer front wall below and adjacent to the refrigerator. A number of spaced horizontally-oriented slats are mounted to the beams to form a web-like slat framework spaced from the front wall of the trailer. Air can thereby flow from the floor between the beams and into the refrigerator inlet. The slats prevent cargo from shifting between the beams and blocking air flow. A similar lattice-style air return bulkhead is sold by Aero Industries (Indianapolis, Ind.).
However, when some types of lattice-style bulkheads are used, there is a possibility that cargo adjacent the refrigerator can shift so that spaces between the cargo provide an air passage between the bottom and top of the refrigerator. Air exiting the refrigerator outlet near the ceiling of the trailer can then be pulled directly downward toward the front wall of the trailer, through the lattice of the bulkhead, and back into the refrigerator inlet, rather than circulating through the trailer by flowing along the trailer ceiling towards the trailer""s rear wall. This phenomenon, known as xe2x80x9cshort cycling,xe2x80x9d sends freshly cooled air into the refrigerator inlet and causes the thermostat in the refrigerator inlet to misread the air temperature in the trailer. The refrigerator then shuts down prematurely, resulting in product thawing and unsafe temperatures for foodstuffs.
To reduce the problem of short cycling, much of the trucking industry has been switching to xe2x80x9csolid-stylexe2x80x9d or xe2x80x9cfalse wallxe2x80x9d air return bulkheads, which provide a solid, continuous wall spaced a short distance from the front wall of the trailer and surrounding the refrigerator inlet. The false wall air return bulkhead is opened near the floor of the trailer to allow air to flow from the trailer floor, behind the bulkhead wall, and into the refrigerator inlet. Because the false wall air return bulkhead provides a barrier between the refrigerator inlet and outlet and an effective refrigerator inlet near the trailer floor, the air exiting from the refrigerator cannot reenter the refrigerator inlet unless it circulates throughout the trailer first. As a result, the false wall air return bulkheads work quite well in preventing short cycling. A summary of prior art false wall air return bulkheads follows.
U.S. Pat. No. 3,206,946 to Lindersmith et al. illustrates a false wall air return bulkhead which includes two parallel panels connected in spaced relation by a number of support beams. One panel (the xe2x80x9cwall panelxe2x80x9d) is attached to the trailer front wall so that the other panel (the xe2x80x9cfloating panelxe2x80x9d) is maintained in spaced relation from the trailer front wall. Warm air from the floor passes between the panels to reach the refrigerator inlet. A series of vertically oriented, generally sinusoidal indentations or flutes are included in the floating panel to enhance heat transfer from the air passing between the panels to the air in the remainder of the trailer.
U.S. Pat. No. 5,427,237 to Kiefer et al. discloses a shipping crate for a refrigeration unit which may be converted to a false wall air return bulkhead. The resulting bulkhead utilizes side rib members which fit vertically on the trailer front wall on either side of the refrigerator, and central rib members which are placed at a diagonal on the trailer front wall beneath the refrigerator inlet. A planar floating panel is then attached to these rib members so that it is supported in spaced relation to the trailer front wall and so that it covers the lower portion of the refrigerator and the refrigerator inlet, thereby isolating the refrigerator inlet from the refrigerator outlet. Pallet stops in the form of C-shaped bumpers are then placed beneath the panel between the panel and the floor. These pallet stops prevent pallets or other cargo from shifting forward during transport, moving under the panel, and blocking air flow to the refrigerator inlet. The pallet stops also prevent pallets or other cargo from sliding beneath the panel and possibly catching and damaging the panel when the cargo is later lifted out of the trailer for removal.
U.S. Pat. No. 4,399,737 to Severson illustrates a false wall air return bulkhead having a floating panel spaced from the trailer front wall. Side support panels descend from the sides of the floating panel and extend into abutment with the trailer front wall near the trailer side walls. Corrugations or flutes are depressed into the floating panel between the panel and the trailer front wall. The top of the floating panel is placed in abutment with the refrigerator adjacent the refrigerator inlet. Supplementary panels or extension members are then attached to the top of the floating panel on both sides of the refrigerator to isolate the refrigerator inlet and prevent air exiting the refrigerator outlet from reentering the inlet. These supplementary panels may include apertures at their sides to allow air adjacent the side walls of the trailer to flow inward towards the refrigerator inlet. The bulkhead is made in several different heights, and the supplementary panels can have several different widths. This allows the bulkhead to be fitted onto differently-sized trailer front walls around differently-sized refrigerators. The bulkhead components are generally constructed of KEVLAR-reinforced fiberglass/plastic composite.
The AERGUARD air return bulkhead (Aero Industries, Indianapolis, Ind.), includes a number of Z-shaped beams which are vertically mounted on the trailer front wall below the refrigerator inlet and near the trailer side walls. Elongated top and bottom floating panels are then mounted horizontally across the tops and bottoms of the beams to leave a central aperture between the beams. A fiberglass reinforced plywood center floating panel is then bolted to the beams between the top and bottom panels to close the central aperture. Bumpers or pallet stops are placed between the bottom of the beams and the floor. Supplementary panels are then placed on top of the top panel on both sides of the refrigerator to complete a barrier between the refrigerator inlet and outlet. A mesh screen may be fit around the inlet portion of the bulkhead, i.e. between the lower panel and the trailer floor and trailer front wall, to prevent debris from entering the refrigerator. A variety of differently-sized bulkheads are sold to allow the bulkheads to be used with differently-sized refrigerators.
An air return bulkhead sold by Donovan Enterprises (LaGrange, Ga.) is somewhat similar to the AERGUARD air return bulkhead noted above. Metal beams are vertically mounted on the trailer front wall near the trailer side walls. A fiberglass reinforced floating panel is mounted to these beams in spaced relation to the front wall. Supplementary panels are then mounted to the top of the floating panel on both sides of the refrigerator to complete a barrier between the refrigerator inlet and outlet.
The prior art also illustrates a xe2x80x9chybridxe2x80x9d air return bulkhead which incorporates features of both lattice and false wall bulkheads. The AIRHEAD air return bulkhead (Air Flo Products, Madison, Wis.) is a lattice-style bulkhead integrally formed of high density polyethylene. The AIRHEAD bulkhead essentially consists of a planar wall panel with a series of raised parallel columns thereon. The wall panel is mounted to the trailer front wall beneath a refrigerator so that the columns are oriented vertically, thereby allowing air to flow between the columns from the trailer floor to the refrigerator inlet. The ends of the columns include apertures so that air can also flow within the columns themselves. Thus, the columns are arranged in a lattice formation, but each column in itself forms a floating wall. The columns are horizontally spaced to such an extent that cargo cannot shift to block air flow between the columns.
However, the prior art air return bulkheads generally tend to have one or more of the following disadvantages.
First, owing to their web-like, largely open structure, the lattice-style prior art air return bulkheads allow air to flow directly against cargo in abutment with the bulkhead, thereby more fully cooling this cargo. However, as noted above, the lattice-style prior art bulkheads can also allow refrigerated air to pass directly from the refrigerator outlet to the refrigerator inlet, resulting in short cycling. False wall air return bulkheads largely prevent short cycling, but at the same time they do not allow refrigerated air to flow directly against cargo adjacent the false wall. As a result, false wall bulkheads may not cool cargo adjacent the bulkhead as efficiently as lattice-style bulkheads. The art is in need of an air return bulkhead which allows efficient cooling of cargo adjacent the bulkhead, but which prevents the occurrence of short cycling at the same time.
Second, the prior art air return bulkheads are time-consuming to assemble and install. Assembly time represents lost trailer use and economic loss, aid for that reason, the art has long been seeking bulkheads which may be rapidly and easily assembled, as well as disassembled and replaced. This long-felt need for an air return bulkhead with lesser installation time is evidenced, for example, by the sales literature for the prior art bulkheads noted above. Such sales literature inevitably touts the installation time of the particular bulkhead to which it pertains. Thus far, a one-hour installation time for a bulkhead has been viewed favorably by trailer owners.
Third, most of the prior art air return bulkheads are not well adapted for convenient display by retailers. Because the prior art bulkheads are somewhat large, retailers generally do not have sufficient space to stock all of the varieties of bulkheads needed to fit all of the different varieties of trailers and refrigerators. At the same time, owing to the wide variety in trailer and refrigerator sizes, it is necessary that the retailer carry a large number of differently-sized bulkheads in order to ensure that a properly fitting bulkhead will be on hand when a trailer owner asks for it. If a properly sized bulkhead is not available, the trailer owner must generally wait two or three weeks for a properly sized bulkhead to be delivered. If the trailer cannot be used in the meantime, this can represent a significant economic loss to the trailer owner.
Fourth, the prior art air return bulkheads are not designed for point-of-sale display in such a manner that they are appealing to consumers. Because most prior art bulkheads are made of a collection of separate panels, beams, and similar components, they generally appear to consumers as no more than an agglomeration of parts in need of assembly. The appearance and fit of the prior art bulkheads generally cannot be visualized by trailer owners until the bulkheads have actually been installed on the front wall of the trailer. In contrast, a bulkhead which uses fewer parts, or a bulkhead which could be presented to customers in substantially assembled form, would be more appealing to consumers.
Fifth, the prior art air return bulkheads are subject to bending and/or cracking or splintering due to the impact of shifting cargo, and due to temperature changes within the trailer. These events can produce sharp edges on the bulkheads which can catch and damage cargo, or injure people working within the trailer.
Sixth, the prior art air return bulkheads, which include air inlets only along their bottom edges, are highly susceptible to clogging. It is a common phenomenon for plastic cargo wrappings, e.g., shrink wrap, to tear during loading or transport and fall off of cargo. The plastic wrap is then blown along the trailer floor and sucked across or into the inlets, thereby crippling the refrigerator""s air intake and preventing air circulation.
Finally, the prior art is also in need of an air return bulkhead which is resistant to damage and collapse from shifting cargo loads; which is lightweight to reduce fuel consumption; which is resistant to rust, mildew and rot, ultraviolet radiation, and/or swelling from water absorption; which can be manufactured of materials approved by the United States Department of Agriculture and the United States Food and Drug Administration for contact with foodstuffs; which does not catch on cargo and thereby cause damage to the cargo (or the bulkhead) when the cargo is being removed from the trailer; which has low friction so that cargo rubbing against it or lifted against it will not be damaged; which is inexpensively manufactured and attractive in appearance; and which is recyclable.
The present invention involves an air return bulkhead which solves the aforementioned disadvantages and which meets the aforementioned objectives. The invention is directed to an air return bulkhead for attachment to a wall having a refrigerator mounted thereon. The bulkhead includes a floating panel having a front face and an opposing rear face bounded by an edge. The edge includes an upper edge portion located at the top of the floating panel and having a size greater than the width of the refrigerator. An upper support panel extends across the entirety of the upper edge portion and descends from the upper edge portion to conclude at a terminal edge. The bulkhead also includes attachment means for mounting the bulkhead to the wall with the terminal edge of the upper support panel in abutment with the wall. After the bulkhead is mounted to the wall, a portion of the upper support panel may be cut away to define a space wherein the refrigerator may be fit.
Unlike the air return bulkheads of the prior art, the bulkhead includes an upper support panel descending from the upper edge portion and extending across the entirety of its length. This support panel may include cut guiding means thereon for guiding a cutting tool, e.g., a small valley wherein a cutting blade may fit, or a ridge against which a cutting blade may be guided. The cut guiding means define a predetermined path which bounds areas sized to accommodate standard prior art refrigerators. Installers can snugly fit the bulkhead on any trailer wall, about any refrigerator, by merely trimming the support panel along the cut guiding means. A space is thereby formed in the support panel wherein the refrigerator can fit so that the support panel and floating panel isolate the refrigerator inlet from the refrigerator outlet. In contrast, prior art bulkheads do not include such a continuous support panel, and instead merely include an aperture adjacent the upper edge portion wherein the refrigerator is fit. To isolate the refrigerator inlet from the refrigerator outlet, this aperture must be closed by supplementary panels or extension members. To fit these prior art bulkheads on different wells about different refrigerators, multiple differently-sized bulkheads need to be manufactured with differently-sized supplementary panels, and these parts require substantial assembly by the bulkhead installer. No prior art references, alone or in combination, teach or suggest the inclusion of the aforementioned support panel or the reduction in manufacturing costs and installation time that it provides.
The air return bulkhead of the present invention is preferably integrally formed of a thin material, most preferably plastic, and it may include other structural features as well. Some of these structural features are as follows.
First, the bulkhead may include a lower edge portion at the bottom of the floating panel, and a support column may rest below this lower edge portion. The support column may include opposing column ends with column walls extending therebetween. Cut guiding means may be included on the support column for guiding cutting tools, wherein the cut guiding means bound an area which may be removed to define an aperture on the support column. The installer can thereby easily add one or more apertures to the support column so that the support column walls define a passage which opens upon the front and rear of the bulkhead, and so that the airflow pattern provided by the bulkhead may be modified as desired. Additional cut guiding means can be added to the support columns to allow them to be cut to a desired length. Multiple support columns may be provided, and their respective heights may be different to obtain desired airflow properties. Web members connecting one column wall on one support column to one column wall on another support column may also be provided.
Second, the bulkhead may include a support flute depressed inwardly from the front face of the floating panel, wherein the support flute includes opposing flute ends with flute walls extending therebetween. The support flute may further include cut guiding means for guiding cutting tools, wherein the cut guiding means bound an area which may be removed to define an aperture on the support flute. By removing these areas, the installer can add one or more apertures to the support flute so that the support flute walls define a passage which opens upon the front and rear of the bulkhead, and so that the airflow pattern provided by the bulkhead may be modified as desired. Additional cut guiding means can be added to the support flute so that it can be cut to a desired length. The flute ends may be formed integrally or separately from the column ends, and the flute walls may be formed integrally or separately from the column walls. Multiple support flutes may be provided, and their respective heights may be different to obtain desired airflow properties.
Third, a side support panel may descend from either or each side edge portion of the floating panel between the upper and lower edge portions. A side webs can then extend from each side support panel to rest on the sides of the floating panel in a plane which is generally parallel to the floating panel. Each side web may include a web support column protruding therefrom, the web support column including opposing web column ends with web column walls extending therebetween. Cut guiding means for guiding cutting tools may be included on the web support column, wherein the cut guiding means bound an area which may be removed to define an aperture on the web support column. The installer can thereby add one or more apertures to the web support column so that the web column walls define a passage which opens upon the front and rear of the bulkhead, and so that the airflow pattern provided by the bulkhead may be modified as desired. Multiple web support columns may be provided, and their respective heights may be different to obtain desired airflow properties. Cut guiding means for guiding cutting tools may further be provided between the side webs and the remainder of the bulkhead so that the bulkhead installer may sever the side webs from the bulkhead if desired, or cut guiding means may be provided on the web support columns to allow them to be cut to a desired length.
Preferably, all surfaces resting between the floating panel and the terminal edge of the support panel, e.g., the support panel, the column walls, and the flute walls, are oriented at an angle of no less than approximately 5xc2x0 (as measured from the perpendicular to the front face) so that multiple bulkheads may be stacked in interlocking fashion for efficient storage and display.
The invention is also directed to an air return bulkhead comprising a floating panel having a front face and an opposing rear face bounded by an edge. The edge includes a lower edge portion and a surrounding edge portion. At least one support panel extends from the surrounding edge portion and terminates in a terminal edge, which may be placed in abutment with a wall to maintain the floating panel in spaced relation to the wall. At least one support flute is depressed inwardly from the front face of the floating panel, and the support flute includes flute walls extending generally between the plane of the front face and a parallel plane which includes the terminal edge. Alternatively or additionally, at least one support column is included below the lower edge portion. The support column includes column walls extending generally between the plane of the front face and a parallel plane which includes the terminal edge. The bulkhead may include one or more of the structural features noted above, such as the side was, side support columns, and cut guiding means located on various areas of the bulkhead.
The invention is also directed to a method of fitting an air return bulkhead on a wall around a refrigerator. First, an air return bulkhead is provided. The bulkhead includes a floating panel having a front face and a rear face bounded by an edge, wherein the edge includes an upper edge portion greater in size than the refrigerator. A support panel extends from the upper edge and terminates in a terminal edge. The support panel is formed of thin material capable of being cut by hand-held cutting means. Second, a portion of the support panel is cut away to form a space sized to accommodate the refrigerator. The terminal edge of the bulkhead is placed in abutment with the wall, with the refrigerator resting within the space. The bulkhead is attached to the wall by use of attachment means.
The method may further include any one or more of the following steps: providing support columns extending from the edge of the floating panel, and cutting apertures in the support columns to modify the bulkhead""s airflow characteristics or cutting the support columns to a desired length; providing support flutes depressed within the floating panel, and cutting apertures in the support flutes to modify the bulkhead""s airflow characteristics; and/or cutting away other portions of the bulkhead, e.g., the floating panel, to allow the bulkhead to fit about the refrigerator or other objects mounted on from the wall, or to modify the bulkhead""s airflow characteristics.
To summarize, the air return bulkhead of the present invention decreases manufacturing costs because a single bulkhead is capable of fitting any size of trailer and refrigerator. Segments of the bulkhead may be cut away by the use of commonly available hand-held cutting tools to rapidly adapt the bulkhead to differently sized trailers and/or refrigerators. As a result, the bulkhead may be modified to fit the trailer and refrigerator in question and installed within fifteen minutes. The bulkhead allows air to flow against cargo resting adjacent the bulkhead, but at the same time it prevents short-cycling and blockage of the air flow between the floor and the refrigerator inlet. The bulkhead prevents shifting cargo from damaging the trailer front wall and/or refrigerator. It does not include any horizontal slats or rungs which can catch cargo being lifted from the trailer, and it has less sharp edges to puncture or otherwise damage cargo or injure personnel working within the trailer. The bulkhead is not as susceptible to bending, cracking, or splintering as the bulkheads of the prior art. The support columns, support flutes, and floating panel of the bulkhead include angled surfaces to allow multiple bulkheads to be stacked in intermitting relation for easy storage and display, thereby allowing sellers to carry a greater number of them in stock with minimal storage space. Additionally, the bulkhead has low weight (approximately 47 lbs or 21 kg), and it may be easily lifted and held against the front wall of the trailer to visualize its appearance and performance. Since the bulkhead is preferably made of plastic, e.g., high molecular weight polyethylene, it is also recyclable; it is not subject to rusting or swelling from water absorption; it can be made resistant to mold, mildew, and ultraviolet radiation; it can be formed of materials which are approved by government agencies for contact with foodstuffs; and it has low friction when rusting or lowering cargo against it.